<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
</head>
<body>
<form action="linked.html"><input type="submit" value="linked"></form>

<iframe name="nav" src="frame.html"></iframe>

<iframe name="nav2" src="frame2.html"></iframe>

<iframe name="nav3" src="frame3.html"></iframe>
</body>
</html>